Atmospheric rivers and moisture transport to Antarctica
Last year, a report by Deutsche Welle highlighted unusual events of moisture transport reaching Antarctica. These episodes are associated with intense atmospheric flows of water vapor known in the scientific literature as Atmospheric Rivers—narrow corridors of concentrated moisture that can transport large amounts of water vapor from the tropics and mid-latitudes toward polar regions.
Under certain atmospheric conditions, these moisture plumes can penetrate deep into the Antarctic continent, particularly affecting West Antarctica. When this occurs, the transported moisture may result in precipitation events. Traditionally, precipitation over Antarctica falls almost exclusively as snow. However, recent observations indicate that some of these events have produced rain, a phenomenon that remains relatively rare across most of the continent.
Despite its extensive ice cover, Antarctica is often classified as the largest desert on Earth in terms of annual precipitation. On average, the continent receives approximately 160 mm of precipitation per year, with even lower values recorded in the interior plateau. In addition, Antarctic air masses are characterized by extremely low humidity, creating a predominantly cold and dry atmospheric environment.
The occurrence of rainfall in such a setting has raised concerns among scientists. Liquid precipitation can accelerate surface melting, promote the infiltration of water into existing fractures within ice shelves, and contribute to structural weakening through processes such as hydrofracturing. When meltwater accumulates or penetrates crevasses, it can increase stress within the ice, potentially leading to ice-shelf destabilization and enhanced ice discharge into the surrounding ocean.
Another important factor is the relatively rapid warming observed in the Antarctic Peninsula. Over the past decades, this region has experienced some of the highest rates of temperature increase on the planet. Warmer conditions increase the likelihood that precipitation associated with atmospheric rivers will fall as rain rather than snow, particularly during episodes of strong heat and moisture advection from lower latitudes.
Taken together, these observations suggest a possible intensification of meridional heat and moisture transport toward Antarctica. If such trends continue, they may have important implications for the stability of Antarctic ice shelves, the mass balance of glaciers, and ultimately the global climate system and sea-level rise.
References
- Deutsche Welle. Reporting on atmospheric rivers and rainfall events in Antarctica.
- Intergovernmental Panel on Climate Change. Sixth Assessment Report (AR6) – chapters on the cryosphere and polar climate change.
- Wille, J. D., et al. (2021). Atmospheric rivers impacting Antarctica. Nature Climate Change.
- Turner, J., et al. (2017). Climate change in the Antarctic Peninsula region. Nature.
- Gorodetskaya, I., et al. (2014). Atmospheric rivers and extreme precipitation events in Antarctica. Journal of Geophysical Research: Atmospheres.